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GOSAT in practice
Takashi Hamazaki, GOSAT Project Manager, Japan Aerospace Exploration Agency
T
he IPCC Fourth Assessment Reports
1
reaffirmed that
the understanding of anthropogenic warming and
cooling influences on climate has improved since the
Third Assessment Reports, leading to very high confidence
that the global average net effect of human activities since
1750 has been one of warming (causes). The prevention of
global warming has become a universal concern, and human
beings, who in the past have been capable of taking action
only after the occurrence of disasters, are now in the position
to take an absolutely remarkable step by standing up for their
future.
Greenhouse gases are currently observed at 264 stations (as of 3
September 2007) around the world, and the data is distributed on
the Internet by the World Data Centre for Greenhouse Gases
(WDCGG). All of these observation points are densely distributed
in the developed nations, while they are sparsely located among
the rest of the world. This current condition results in estimating
an average measure of global warming, but not in details by regions
or seasons. Especially with regard to oceans, it is all but impossi-
ble to know where and how much carbon dioxide (CO2) is
absorbed and emitted.
Thanks to a large number of institutes working on global-
warming issues, many local phenomena have been observed and
reported. For example, in the Amazon rainforest, scientists have
found that methane is released from rotten tree roots after the river
floods during summer, and in Siberia, it has been observed that
melting permafrost is producing methane. However, there exist
no comprehensive worldwide global warming data in
two-dimensional view like a world map.
The Greenhouse Gases Observing Satellite (GOSAT)
will be the first observatory that will steadily and glob-
ally monitor greenhouse gases at 56,000 observation
points. The satellite will monitor the entire globe in
three days, orbiting 14 times a day at an altitude of
666 km. With ground-based observation, a different
observation instrument is used for each location, but
GOSAT requires only a single instrument. This capa-
bility of acquiring global data every three days is one
of the major features of GOSAT.
GOSAT has three major mission objectives. The first
is to monitor the density of greenhouse gases precisely
and frequently worldwide. Greenhouse gases are the
major cause of global warming. CO
2
represents 60 per
cent of greenhouse-gas effects; methane makes up
another 20 per cent. GOSAT will measure the distrib-
ution and density of these two main greenhouse gases
in detail.
The second mission objective is to study the absorp-
tion and emission levels of greenhouse gases per
continent or large country over a certain period of
time. The Kyoto Protocol, which came into effect on
February 2005, requires that developed nations reduce
greenhouse gas emissions between 2008 and 2012.
The target for Japan is six per cent below 1990 levels;
for the European Union it is eight per cent; however
Source:
World Meteorological Organization (WMO)/World Data Center for Greenhouse Gases (WDCGG)
• 264 stations scattered around the world
• The data from stations are distributed from WDCGG of WMO
• The number of stations is limited, and stations exists
unevenly in the world
GHG observing points
• 56,000 points, every 3 days
• Global and frequent observation with single instrument onboard
S
OCIETAL
B
ENEFIT
A
REAS
– C
LIMATE